(Revised) Description: Phoenix Biosystem is developing enabling technologies for continuous monitoring of analytes by adapting technology from the University of California. While a great many innovative technologies have been proposed, only a fraction are in advanced stages of development. Blood gas, electrolyte and glucose values are a necessary diagnostic measurement in the management of critically ill, ventilated patients in the intensive care unit (ICU). The frequency of blood sampling is usually determined by the severity of the condition and clinical practice. A drawback to scheduled blood sampling is that changing conditions may be missed. In critical situations the practitioner may have to wait for a blood sample to be drawn and taken to the laboratory, which may or may not be in close proximity to the ICU. With the advent of continuous monitoring, treatment modalities can be proactive rather than reactive.